1. Field of the Invention
The present invention generally relates to an automatic transmission control arrangement. More specifically, the present invention relates to control of an automatic transmission in a temporary disabled mode while in Drive in order to reduce heat generation.
2. Background Information
An automatic transmission of a vehicle typically includes a torque convertor that transmits rotary power from an engine of the vehicle to the automatic transmission. The torque convertor is a fluid coupling device that basically includes a pump section, a fixed stator and a turbine section. The pump section of the torque convertor is directly connected to the output shaft of the vehicle engine and rotates therewith. The turbine section of the torque convertor is directly connected to an input shaft of the automatic transmission. The fluid pressure generated by the pump section causes the turbine section of the torque convertor to rotate. At high engine RPMs (revolutions per minute), the fluid pressure generated by the pump section forces the turbine section to rotate. At low engine RPMs, the pump section generates a lower level of fluid pressure, such that the turbine section can stop rotating, such as when the vehicle is at a complete stop and is in “Drive”.
When the automatic transmission is in “Drive” and the vehicle is at a complete stop, the torque convertor generates a certain amount of heat due primarily to the fluid shearing friction generated by the pump section and received by the non-rotating turbine section (the turbine section cannot rotate with the automatic transmission in “Drive” and with the vehicle at a complete stop). Hence, when a vehicle is at a complete stop (with no motion) and the transmission is set in the “Drive” mode of operation, the automatic transmission generates heat. Typically, a vehicle is at a complete stop while in “Drive” for only a brief period of time (for instance, at a stop light). Therefore, heat generated by the automatic transmission is usually dissipated once the vehicle is in motion again. However, when the vehicle is at a complete stop and in “Drive” for an extended period of time, the dissipation of the heat generated by the automatic transmission can be a burden on the cooling system of the vehicle, in particular on an extremely hot day.